1. Field of the Invention
The present invention relates, in general, to a relay module for a vehicle battery system and, more particularly, to technology related to a relay module which constitutes a part of a power relay assembly provided in a battery system mounted in a vehicle in order to supply power that is used to drive a vehicle, such as a hybrid vehicle or electronic vehicle referred to herein as environment-friendly vehicles.
2. Description of the Related Art
A battery system mounted in an environment-friendly vehicle is configured, as shown in FIG. 1, wherein a part indicated by a dotted line denotes a Power Relay Assembly (PRA) 500. Such a PRA 500 functions to guarantee a high degree of electrical insulation and electrical safety between vehicle systems, and also functions to prevent the occurrence of secondary significant accidents such as an electric shock caused by a high voltage or fire attributable to an electrical malfunction when an accident occurs. The PRA 500 may also be utilized to block dark current flowing from a high-voltage battery.
The above-described power relay assembly 500 is configured to include a positive (+) main relay 502, a negative (−) main relay 504, and an initial charging relay 506. Control of a relay ON sequence is implemented as follows: when the vehicle enters an ignition ON state, the negative main relay 504 is turned on and thereafter the initial charging relay 506 is turned on, thus enabling a peak current caused by a resistor to be restricted. After the positive main relay 502 is turned on as the charging of a capacitor has been completed, the initial charging relay 506 is turned off, completing the control of the relay ON sequence. Thereafter, control of a relay OFF sequence is implemented such that when the vehicle enters an ignition OFF state when in a state in which the initial charging relay 506 is turned off, the positive main relay 502 and the negative main relay 504 are simultaneously turned off.
In a Battery Management System (BMS), in order to diagnose faults such as the welding of relays operated as described above, diagnosis has been indirectly conducted using logic based on a series of operations involving each relay operated as described above. Such indirect diagnosis based on such logic is disadvantageous in that when the vehicle is started, only such faults as the welding of relays and a failure in the open circuit of the initial charging relay 506 can be diagnosed, so that when a problem occurs while a relay ON sequence is activated, it is difficult to determine whether the problem is caused by the relay itself, an error in the internal control circuit of the BMS, or a disconnection or short circuit of a control output wire. Further, even if the problem is determined to be with the relay itself, it is impossible to accurately determine whether the problem is caused by the welding of the contact point of the relay, whether the problem is caused by a failure in an open state, or wherein the problem has occurred, (i.e., the positive main relay 502, the negative main relay 504, and the initial charging relay 506).
Therefore, there are problems in that when a fault occurs in the relay that is part of the power relay assembly 500, it is impossible to immediately and accurately diagnose the problem. Furthermore, when only a specific relay is replaced based on the determination of a relay-related fault, there is a probability that an actual faulty relay may not have actually been replaced, thus causing the vehicle to be exposed to an unexpectedly dangerous situation. Additionally, when the vehicle is inspected, operating efficiency in fault recovery is greatly decreased in such a way that relays and a BMS must be individually replaced and then checked in relation to fault detection, thus resulting in temporal and economic loss.
The foregoing is intended merely to aid in the better understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art as already known to those skilled in the art.